The invention relates to an apparatus and a method for supplying a continuous tape.
Specifically, but not exclusively, the invention can be used in the context of an apparatus for forming labels from a continuous tape (generally unwound from a reel) that has, distributed along the length thereof, a series of images that are preprinted and spaced apart from one another by a preset space (pitch) and will form the images on the labels.
As known, this pitch can be variable from one reel to another according to requirements, or even, can vary in the context of the same reel, sometimes also because of printing or unwinding errors.
A problem with known printing apparatuses is thus that of forming some labels from a continuous tape bearing the images, in which each image is centred on the label, whatever the pitch of the images distributed along the tape, even in the event of printing or unwinding errors that may have modified the nominal pitch of the images and/or may have distorted the images with respect to the desired distribution.
In order to overcome this problem, from WO 2006/061775 a continuous tape feeding apparatus is known in which a feeding device advances a tape along a path, a sensor detects an image on the advancing tape, a cutting device cuts the tape transversely into labels and a controller compares the detected image with a reference image and then adjusts the advancing speed of the tape on the basis of the aforesaid comparison in order to cut the tape in the correct position to form labels with a perfectly centred image.
The sensor used in the apparatus disclosed in WO 2006/061775 for detecting the image is a pixel optical sensor, or a band optical sensor that emits a signal indicative of the average value that a given optical feature assumes (for example luminous intensity) in a preset portion of the surface of the tape. Various aspects of the apparatus shown by WO 2006/061775 are improvable.
In the first place it would be advantageous to eliminate or minimise the risk of errors in the forming of the label that are due to a programmed or not programmed or also undesired variation in the operating parameters of the cutting device in the course of advancing of the continuous tape.
In the second place it would be desirable to improve the precision and reliability of the known apparatus, for example by reducing the negative effects due to possible transverse movements of the tape in relation to the advancing direction thereof, effects which may compromise the correct operation of the apparatus in WO 2006/061775. It has been observed that in WO 2006/061775 the use of the band sensor, that on the one hand can help reduce to a certain extent the imprecision due to undesired transverse movements of the tape and on the other hand is imprecise through the nature thereof.
It would be further desirable to improve efficacy in monitoring the print quality of the image in the tape and/or in recognising malfunctions of the feeding apparatus (for example errors in mounting the reel and/or the tape) and/or in identifying the size of the tape and of the corresponding label.